The human spinal column provides support for the body while also protecting the delicate spinal cord and nerves traveling along the spinal column. In general, the spinal column comprises a series of vertebrae stacked on top of each other with an intervertebral disc between each vertebrae. The intervertebral discs advantageously provide cushioning and dampening of compressive forces to the spinal column. For various reasons, including traumatic injury or natural causes, the intervertebral discs may be damaged or otherwise compromised. In such cases, it is known that intervertebral disc replacement devices, such as fusion devices, may be inserted to replace the failing disc or a portion thereof. In order to facilitate placement of such devices, the disc may be removed in whole or in part and the intervertebral disc replacement device inserted between the vertebral bodies. During this procedure, adjacent vertebrae may be distracted by a distraction instrument to assist with the removal process, endplate preparation, or other portions of the procedure.
Present distraction instruments include wedges that may be inserted into the disk area for temporarily supporting the spinal structure. Conventional wedges may be threaded onto an installation tool, which typically comprises an elongated shaft with a handle, the shaft having external threads at its distal end for engagement with internal threads of the wedge. Once inserted, the tool may be rotated and unthreaded from the wedge with the wedge left in place temporarily distracting the adjacent vertebrae. The unthreading of the tool from the wedge distractor is certainly time consuming and may be difficult because of cross-threading. Alternatively, the tool may be left in place while other portions of the overall procedure are undertaken by the surgeon. However, this leaves the tool in the surgeon's line of sight.
Even after tool removal, reattachment leads to more time consumption and cumbersome work. When a wedge is left in place without the tool, and it is desired that the wedge be removed, the surgeon may rethread the tool onto the wedge, and pull the wedge from within the disk bore. It may be difficult, however, for a surgeon to achieve this rethreading because of limited access and visibility. For example, it may be difficult for a surgeon to locate the internally threaded aperture of the wedge with the distal end of the tool. Even when it is located, it is then difficult to thread the tool into the wedge without the tool becoming disengaged from the wedge during the rotation process. There is also the possibility of cross-threading on reattachment.
Accordingly, there remains a need for a tool that can insert a distraction wedge easily and accurately, and can then be reattached quickly and securely to the wedge for wedge removal.